Why wont my canaries get along after 8 months?

what is the reason for this? i planned on having a happy canary family. is it because they dont get right amounts of light? because my family has a habit of turning the lights off and not giving the canaries enough light for breeding season. even though i tell them to leave it on. there is a divider between their cage. why are they still squawking at eachother? what is the reason for this? please someone answer